ef 50mm 1:1.4 poor performance with back light

[jakobl]

Recently I took some outdoor photos with my ef 50mm 1:1.4. It was in a kind of

canyon. The sun had disappeared and most of the light was comming from the

front. I thought that a faster lense would perform better in this lower light

situation.

To my suprise none of the pics turned out to be good.

None of the pics were sharp, some were really out of focus.

The chromatic aberration was huge (I think ca is the right term).

 

Is the 50mm simply the wrong choice in this situation, should I buy a lens hood

or was it something different?

 

Jakob<div></div>

[adzy]

Couple of questions that would help peopel identify the problem-

 

Is the enclosed image a crop or is 100% as shot ?

 

Did you shoot raw or jpeg ?

 

What ISO, shutter speed, aperture where you shooting at ?

[kit_chong]

This is very strange for me. I have the same lens as you described and never had your results. Is it all the time like this?

[jakobl]

thanks for your interest.

 

@Azi: more info: This is a crop, I shot in jpg, aperture 1.4, ISO 100, speed 1/30s

I know the shutter speed is not that much but I have another one at 1/60 s with similar results. I will post that as well.

 

@Kit: most of the time the lens makes great pics<div></div>

[PuppyDigs]

I have not seen "purple fringing" with this lens on film, but all my lenses--L or otherwise--

exhibit it on high contrast and/or overexposed situations with digital. My feeling is it is not

true CA (no rainbow) but a sensor artifact.

 

As for AF, my EF 50 1.4 USM had more trouble in low light and backlit situations than any

lens I have owned. Even my EF 28-105 3.5-4.5 USM was much better in this respect.

[brucecyr]

The facile answer is to avoid shooting in canyons just after sundown :-)

 

Are you using the 20D? 1/30 and 1/60 aren't particularly fast speeds for that lens/body combination. Given the lens is effectively 80mm on that body, 1/100 of a second would be recommended to counteract camera shake.

 

I hope its not out of place to suggest that at f1.4 the DOF is very narrow. If AF is not working properly due to low light conditions, then its tricky to conclude pics were not sharp -- maybe they were sharp at the actual focal plane! Or maybe the shutter speed just wasn't fast enough for the conditions. It would help to see the uncropped images.

 

If you can re-visit the same or similar conditions/site, try a higher ISO with manual focusing and maybe a more clearly defined focal plane. Also try varying apertures. You may conclude your results are due to your techniques.

 

BTW, photos in your portfolio here are nice!

[jakobl]

I think you are right with the shutter speed (and with the 20d).

But IMO this is only one part of the problem. Of course DOF is very narrow but it's also depending on the distance of the object and my object was about 3 meters away and the canon site says the DOF at Near Distance is about 2.85 meters. So I think it's no real problem of DOF.

But what I noticed with this pic is that the background is a little sharper, so maybe the cam focused on the stones in the bg.

Never the less normally most of the pictures are quite good, at this day there was no good/sharp picture.

Any explaination of the imense chromatic aberration?<div></div>

[jakobl]

At this size the picture looks sharp in the background but actually it isn't

[fourfa]

this lens isn't great at f1.4, low contrast, hazy, and some veiling like you posted. stop down to f2 and it's worlds better. on the other hand if you nail focus (can be difficult), the veiling makes for flattering B&W portraits

[brucecyr]

"my object was about 3 meters away and the canon site says the DOF at Near Distance is about 2.85 meters."

 

I apologize because the way you identified your shot above led me to assume, falsely, that you were shooting at f1.4. Obviously, the aperture is much smaller than that -- "1.4" simply identifies the lens.

 

Nevertheless, at the size posted the uncropped shot doesn't look horrible to me. The focal point is clearly further down the canyon. But if its not sharp anywhere, it seems to me camera shake is the culprit.

 

The crop you posted initially is such a miniscule portion of the whole image that its unrealistic to make any deductions about problems with the lens -- especially since its not at the focal plane. Seems to me you're practicing the vice of pixel-peeping :-)

 

Next time use support and focus manually.

[derek_stanton2]

The 50/1.4, wide open, is know for that 'halation' effect, where white areas bloom and bleed.

Closed down a bit, the effect goes away. I imagine there is sample variation, so maybe your

lens is worse in this respect than others?

[digitmstr]

Shooting wide open for such a "long shot" is not a good idea. Your DOF will be basically nill. Clearly, the lens/camera combo did NOT focus on the person walking on the bridge.

 

As for the aberration, I see some it's blue and some it's purple. Because it's located at the center I think it may likely be sensor bloom caused by the white hat against the darker, surrounding area, rather than CA. I say this because I have never had that happen with my 50mm even at f/1.4 in 'worse' conditions (i.e. where I would have expected it to exhibit such CA).

[gdanmitchell]

Assuming that you were shooting on a DSLR (and not a film SLR) it would make a whole lot

of sense to up the ISO to 200 or even 400 and shoot at a faster shutter speed, and even a

slightly smaller aperture. (I'm assuming you shot at f/1.4.)

 

f/1.4 on the EF 50mm lens is known to be soft so generally avoid the wide open aperture

unless you have no option. And at ISO 100 you have the option of higher ISO.

 

I do think that the problem is more than just the naturally soft image of this lens at f/1.4.

If you weren't using a tripod and you shot at 1/30 you were below the 1/focal length

shutter speed (e.g. 1/50 sec) and while not perfect, this rule of thumb is a good starting

point for selecting longest exposure for carefully handheld shots.

 

In addition, it looks like your subject was moving. Also, the white hat is probably quite

overexposed - looks like it burned out and that is perhaps contributing to the general

fuzzy effect.

 

Did you shoot jpg or RAW. If the latter (and possibly if the former, depending upon your

camera settings) you will need to do some sharpening in software. (Not that this will

completely resolve the issues, but it generally improves things.)

 

All of that said, without more information we can't rule in or out the possibility that there

is a problem with the lens (or camera) without better information. A good test would be to

put the camera on a tripod, use MLU and a remote shutter release or timer, and take

photos of subjects that provide good contrast to enable good autofocus. Try at f/8 for

best sharpness and then try at larger apertures, all the way to f/1.4. If your image is sharp

at f/8 and pretty decent at f/2 or so but deteriorates a bit at f/1.4... that is normal for this

lens. If it isn't decent at f/2.8 or so you may have a problem. On the other hand, if it looks

decent in this kind of controlled test you probable can look elsewhere for the explanation

for these soft shots - e.g. see my post and others here.